Nolan, that's a very good point, and I know exactly, what you mean.
"Smelling" the lens image is very nice...
Let me make a little correction: perspective is not made by the focal lenghts, but the camera position. So a crop from a a wide angle has ecaxtly the same perspective as a tele!
The different °foreground to background relationship° - I call it °image-space° - draws a important line between the different angles of the lenses.
It's not alwith possible to use just one lens; beeing in a small room with the idea to show it entirely, p.e. makes it hard. But still keeping the choice of lenses on 2 focal lenghts trough a entire serie - a 28 mm & 50 mm on FF, just a example - produce a nice interplay of two °visions°.
One solution to keep the °foreground to background relationship° constant is stitching; while enlarging the FOV, the °image-space° remains identical. It works....
It's true that perspective is determined by subject distance and vantage point. That's a valuable clarification. I think that one reason some people associate perspective with focal length is that they tend to be closer with wide angle lenses, at more middle distances with mid-focal length lenses and further away with longer lenses. That's not always the case but I think that it is, in part, why people start to get a certain sense of perspective from their various lenses.
People often talk, for example, about the sort of perspective they perceive when using, lets say, a 15 mm lens. And for a given framing with that lens, they might be, say, ten feet from a subject. To keep the same framing with a 50, one would have to back up considerably and that change in camera distance would indeed change perspective. So, I think its the net experience that some may be thinking of when they associate perspective with focal lengths. The two are not directly related but they often end up being indirectly associated in practice.
Cheers,
Sean